JavaScript function return multiple values as object in ES6
function function_name()
{
var a=1;
var b=2;
return {a, b}
}
let {p1, q1} = function_name()
Why do I get the error message p1
, q1
how undefined
? However, the code below gives the expected results:
var o = {p: 42, q: true};
var {p, q} = o;
console.log(p); // 42
console.log(q); // true
Can anyone explain the difference between the two code examples?
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You get the desired result because function_name () returns an object that has two variables a and b that have some value.
function function_name()
{
var a=1;var b=2;
return {a,b}
}
here is return {a, b}
equivalently return {a: a, b: b}
equivalentreturn {a: 1, b: 2}
To get the exact value, you need to update the calling method signature:
let {a, b} = function_name()
Note . It is bad practice to use the variable name a or b. You must use valid names.
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This is a destructuring that uses the keys in curly braces to get values with the same job key. Your function reconfigures the object
{ a: 1, b: 2 }
and then you want to get properties named p1
and p2
. Obviously, there are no keys with these names in this object, and therefore there is no property as a result.
{ a: 1, b: 2 } => get { p1 and p2 } => {}
Working example
{ p: 42, q: true } => get { p and q } => { p: 42, q: true }
With a different property
{ p: 42, q: true, foo: 42 } => get { p and q } => { p: 42, q: true }
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